Comparison of Three Assays for Total and Free PSA Using Hybritech and WHO Calibrations

Background/Aim: Lack of interchangeability between prostate-specific antigen (PSA) assays could have a clinical impact. We compared PSA assays from different manufacturers and calibrations. Patients and Methods: A total of 233 men who underwent prostate biopsy (PSA: 2-10 ng/ml; Beckman Coulter Access (R) Hybritech (R) as reference) were enrolled. Total (tPSA) and free PSA (fPSA) were also measured using the Roche cobas (R) and the Abbott Architect (R) methods. Results: Roche tPSA values were approximate to 1% higher than Beckman, while Abbott values were approximate to 5% lower. Roche had the highest diagnostic sensitivity (92%) compared to Beckman Coulter (87%) and Abbott (85%). Roche fPSA was approximate to 3% lower and Abbott approximate to 17% higher than that of Beckman. For the percentage of fPSA, Roche had the highest sensitivity (98%). Conclusion: Roche cobas (R) and Beckman Coulter Access (R) Hybritech (R) tPSA were almost interchangeable. While the agreement was acceptable for tPSA, this did not happen with fPSA and greater efforts for harmonization are required.

Automated summary

The study compared PSA assays from different manufacturers and calibrations, finding that Roche and Beckman tPSA were almost interchangeable, but there were discrepancies in fPSA, indicating a need for greater harmonization efforts.